In order to test various oxidizable materials such as ore, ash, slags, or heat-resistant materials of a similar nature it is necessary to melt these materials and cast tablets or slugs of them. Then the tablets or slugs can easily be analyzed by X-ray or fluoroscope techniques.
Thus it is normally necessary to melt in a small crucible, normally of platinum, a predetermined quantity of the material to be tested. Hence the material is melted and the entire melted mass inside the crucible is agitated to make it homogenous. Meanwhile a mold for casting a tablet or slug is preheated to a predetermined temperature. The homogenized molten material is then poured into the preheated mold which is then slowly cooled, whereupon a tablet or slug of predetermined size can be turned out of the mold.
Obviously the nine steps involved -- filling the crucible with premeasured quantities, pouring the measured dose into the crucible, heating the crucible to melt the material, agitating the crucible to homogenize the material, prewarming a mold, pouring the homogenized and melted material into the mold, cooling the mold, turning the slug or tablet out of the mold, and cleaning the mold and crucible for reuse -- take considerable time and represent an onerous succession of tasks.
Thus a machine is known having a carrousel with a plurality of angularly spaced holders for the crucibles. A crucible in one of the holders can be displaced angularly past one or more bunsen burners and a gas jet suitable for cooling the crucible. The operator must therefore charge into each crucible a quantity of the material to be tested along with the typical salt additive necessary for proper analysis later, then move the thus-filled crucible into position over the first burner. Once it is melted the material is agitated by hand over the second burner and thereafter emptied into a platinum mold that has been preheated, but can be afterward displaced over the air-cooling nozzle. This arrangement somewhat simplifies the operation, but nonetheless requires that virtually every stage be done by hand.
With such a semiautomatic arrangement it is possible to process a normal batch in approximately 32 minutes overall. Eight minutes are needed over the two burners to properly heat and homogenize the material, then the material must rest at least four minutes as it cools and hardens. Since two burners are provided it is therefore possible to complete a tablet every four minutes, using normally two operators to man the apparatus and make the slugs. If only six slugs are needed it therefore takes two men 32 minutes to form them. When a larger quantity is needed the amount of man-hours consumed is considerable, especially since two people must be employed, one operating the apparatus and another cleaning and refilling the crucibles.